Between joist underfloor heating output requirements

[Lamentable]

I am thinking about installing between joist UFH in an old 1930's house with 200mm solid walls.

The room I am looking to fit it to is as follows:

18m2 floor space
2.6m height
2 external walls one which contains a large bay window which has pretty crap efficiency due to metal internal spacer bars.

The room is currently fitted with a 1200 x 600 type 22 radiator which has an output of 2000w.

My question - do I need the UFH system to also output 2000w?

If yes, I would need a between joist system that outputs ~ 110w/m2 and I am struggling to find something like this. Most of the systems output between 60-80w/m2 and require 55 deg. C flow temp to achieve the higher end of that range.

Also, what sort of flow temp should I be targeting to maximise efficiency of the condensing boiler?

Renovations would also include insulting between joists, insulating both external walls and changing the window for a more modern unit.

Thanks in advance.

 

[cross thread]

Just because you have a 2 kw rad now doesn’t mean it was ever calculated , use a online calculator and input your room sizes first

 

[Lamentable]

I've run the calculations on the room and it needs 2kw.

Living room
Height = 2.6m
Width = 4.0m
Length = 4.2m
Outside Walls = 2
Outside Wall Construction=220mm solid brick
Windows = Plastic double glazed.
Below room = Soil under wooden floor
Above room = Heated room

1990w
6791 BTU

2000w / 16.8m2 = ~ 120w/m2

I think it's a bit of a risk to fit a system that could offer at best around 70w/m2.

Probably better to insulate the floor and stick with the radiator. Less upheaval as well.